1. Field of the Invention
The present invention relates to an image forming apparatus which collects into a collection container waste toner particles generated by an operation of forming an image onto a recording sheet.
2. Description of the Related Art
Conventionally, an image forming apparatus adopting an electrophotographic method has been widely known. The image forming apparatus forms an image on a recording sheet by performing an exposing operation based on a image data to form an electrostatic latent image on a surface of a photoconductive drum uniformly charged with electricity, forming a toner image by a developing section adapted for developing the electrostatic latent image with toner particles, directly or indirectly transferring the toner image onto a recording sheet, and fixing the image on the recording sheet.
In this kind of image forming apparatus, toner particles generally remain on an image bearing member such as a photoconductive body or the like after the toner image transferring operation is performed. Therefore, a cleaning device is provided for removing the unneeded toner particles (hereinafter, referred to as waste toner particles). Further, a developability of toner particles which have not been used in the image forming operation and remained in a developing section for a long period of time is degraded. Accordingly, a printed image quality is also degraded. Therefore, the toner particles having a degraded developability or removed in the cleaning device (hereinafter, referred to as waste toner particles) are collected and stored in a detachable collection container (refer to Japanese Unexamined Patent Publication No. 2004-240369).
In such image forming apparatus, if an image forming operation is continued after the collection container is filled with waste toner particles, the waste toner particles overflow from the collection container. Therefore, when the amount of waste toner particles stored in the collection container is nearly full, the image forming apparatus warns a user that the collection container is full to induce the user to replace the collection container or suspend the image forming operation.
Meanwhile, even after warning that the collection container is nearly full, waste toner particles can be collected to some extent. Accordingly, there is a case where a user would like to continue an image forming operation to some extent. In the above-described image forming apparatus, there has been a disadvantage that the image forming operation is immediately suspended when the warning that the collection container is filled is given even though more waste toner particles can be collected to some extent. To continue the image forming operation to some extent even after the warning that the collection container is filled is given, while preventing the waste toner particles from overflowing, it may be so configured as to give the warning in a state where there is a great remaining volume of the collection container to be filled. However, in such case, if a user replaces the collection container immediately after the warning is given, it is assumed that the collection container is replaced while leaving a large space. Accordingly, there has been a disadvantage that a volume of the collection container cannot be utilized effectively.